NEW YORK (Reuters Health) - Infection with hepatitis C virus (HCV) worsens the neuropsychological impact of advanced HIV infection, according to a report in the March 23rd issue of Neurology.

Both HIV and HCV are associated with cognitive dysfunction, the authors explain, and the prevalence of HCV among HIV-positive individuals ranges from 30% overall to as much as 90% in injection drug users.

Dr. Elizabeth L. Ryan and colleagues from The Mount Sinai Medical Center, New York compared the neuropsychological profiles of 67 individuals coinfected with HIV and HCV with those of 49 individuals infected with HIV alone.

HIV+/HCV+ patients were more likely to have a past history of drug dependence, the authors report, and substance-induced major depression was the most prevalent syndrome among these individuals. Otherwise, the groups did not differ in the rates of primary mental disorders.

HIV/HCV-coinfected patients tended to perform worse on neuropsychological tests, the results indicate, showing significantly more perseverative responses on the Wisconsin Card Sorting Test and a higher level of impairment in the executive functioning domain than the patients infected only with HIV.

"Our ability to detect greater impairment is surprising given that HIV and HCV appear to have similar patterns of neurocognitive disruption and advanced HIV is associated with significant cognitive decline," the investigators write.

Both groups had compromised functional ability, the report indicates, but there were no significant differences in activities of daily living complaints between the two groups.

"While highly active antiretroviral therapy (HAART) controls HIV viral replication, replication of HCV is not inhibited by HAART," Dr. Ryan told Reuters Health. "Thus, although the incidence of HIV-associated dementia has decreased in the HAART era, the current emergence of HIV/HCV coinfection may lead to increases in cognitive disorders."

"HIV-positive individuals (especially current or former intravenous drug users) should be screened for HCV and coinfected patients should be routinely monitored for evidence of hepatic dysfunction and emergence of viremia," Dr. Ryan said.